This application is related to U.S. patent application No. 08/853,833, entitled xe2x80x9cCommunications System,xe2x80x9d filed May 9, 1997, now U.S. Pat. No. 6,204,810, and U.S. patent application No. 09/064,525 entitled xe2x80x9cCommunication System,xe2x80x9d filed Apr. 23, 1998, now U.S. Pat. No. 6,271,790, the entire contents of which are hereby incorporated by reference.
This application is related to the subject matter of the following U.S. applications filed concurrently: U.S. patent application No. 09/436,236 entitled xe2x80x9cAdjustable Balanced Modulator,xe2x80x9d pending, U.S. patent application No. 09/436,531 entitled xe2x80x9cSystem For Measuring and Displaying Three-Dimensional Characteristics of Electromagnetic Waves,xe2x80x9d now U.S. Pat. No. 6,295,025, U.S. patent application No. 09/436,144 entitled xe2x80x9cCavity-Driven Antenna System,xe2x80x9d now U.S. Pat. No. 6,317,097, U.S. patent application No. 09/437,892 entitled xe2x80x9cDisc Antenna System,xe2x80x9d now U.S. Pat. No. 6,340,950, and U.S. patent application No. 09/436,400 entitled xe2x80x9cTwo-Dimensional Amplifier,xe2x80x9d pending.
The present invention relates generally to transformer systems. More specifically, the present invention relates to a transformer system used in a communication system to perform two dimensional filtering.
Known communications systems use, for example, filters to respond differently to signals of different frequencies. Passive filters, for example, are constructed with passive elements such as resistors, inductors and capacitors. Filters can be categorized by type: low pass filters filter out higher frequencies, high pass filters filter out lower frequencies, bandpass filters filter out lower and higher frequencies while passing middle frequencies defined by the pass band, notch filters pass lower and higher frequencies while filtering out middle frequencies defined by the stop (or notch) band.
Used in conjunction with a communications receiver system, filters operate on electrical signals detected by the receiver system based on the electromagnetic wave received at the receiver antenna. In the context of a communications transmitter system, filters operate on electrical signals produced by the transmitter system and propagated as an electromagnetic wave via the transmitter antenna. In the communications system context, filters can remove electrical signal components at particular frequencies that are undesirable and can represent, for example, unwanted noise, harmonics, and/or intermodulation products.
These known filtering techniques for communications systems, however, suffer several shortcomings. These filtering techniques are xe2x80x9cone-dimensionalxe2x80x9d in the sense that the filtering is performed regardless of the orientation of the electromagnetic wave received and transmitted by the communications system receive antenna and transmit antenna, respectively.
In other words, these filtering techniques are of limited use to process signals that are based on information-modulated electromagnetic waves having a particular and varying orientation, for example, to establish a particular information channel. For example, such an electromagnetic wave can have a carrier frequency and an electric field the terminus of which traces a non-linear path at a second frequency between the carrier frequency and zero. Above-mentioned U.S. patent application No. 09/064,525 (xe2x80x9cCommunication Systemxe2x80x9d) discloses a communications system that utilizes such an electromagnetic wave.
In view of the foregoing, a substantial need exists for filtering techniques that account for the orientation of the electromagnetic wave received by a communications receiver and transmitted by a communications transmitter. Such filtering techniques can be referred to as xe2x80x9ctwo-dimensionalxe2x80x9d filtering.
Two-dimensional filtering for a communications system can be performed by a transformer system. The transformer system comprises a transformer star winding to be coupled to an antenna system, and a transformer delta winding disposed with said transformer star winding. The transformer star winding includes a set of star elements and the transformer delta winding includes a set of delta elements each being substantially perpendicularly disposed with a corresponding star element from the set of star elements.
In one embodiment, the antenna system includes a set of antenna elements. The transformer star winding includes a set of star elements the number of which are substantially equal to the number of antenna elements in the plurality of antenna elements. The transformer delta winding includes a set of delta elements the number of which are substantially equal to the number of antenna elements in the plurality of antenna elements.